Marine steam-turbine.



C. G. CURTIS.

` MARINE STEAM TURBINE.

APPLmATIoN rILBD Nov. 19, 1910.

Patented Nov. 14, 1911.

4 S IEETBSHEET 1.

0. G. CURTIS. MARINE STEAM TURBNB. APYLIGATION FILED Nov.1s.191o.

Patented Nom-'14, 1911.

4 E NIETS-SHEET 3.

:Inventor @wy/@ir Witnesses C. G. CURTIS.

MARINE STEAM TURBINB.

APPLIOATIQN FILED Nov.19,1910.

L 1 9 1 4, ,1 V. N d nu t .n ...u na D..

4. T E E u T E E H s l.

i Irwentor C@ qm N HW Attorney.

UNITED sTATEs PATENT oEEIoE.

CHARLES e. CURTIS, or NEW Yonx, N. Y.

i l MARINE STEAM-TURBIN E.

Specification of Letters Patent.

Patent ed Nov. 14,1911.

Application led November 19, 1910. Serial No.' 593,160.

7,'0 al( whom it may concern: i

Beitknown that I, CHARLES G. CURTIS, a citizen ofthe United States,residing at New York city, in the county and State of New York, haveinvented a certain new and useful Improvement in Marine Steam-Tui'-bines, of which the following is a specification.

` thrusts, including that of the propeller, by

reversed drum pressurestages, set vforth in that application, is madeuseful in a marine steam turbine having turbine elements operated atdifferent steam pressures-on the same shaft. In a turbine o f this,character it is important that the two elements of the turbine on thesame shaft should be independent of each other with respect tolongitudinal expansion and contraction, and hence it is usual todividethe shaft between the two elements and connect the two sections ofthe shaft'together by a coupling permitting a. longitudinal slip. Thetwo shaft sec-v tions are held against longitudinal movement byindependent thrust blocks and the propeller thrust is taken only by onesection of the shaft. Heretofore -in the construction of marine steamturbines o f this character having initial jet impulse stages, and builtin two elemen ts complete on one shaft, it has been the practice toemploy in the high pressure element a number of wheel stages only,which, having ythe same steam pressure on opposite sides of the wheels,avoidthe production in this yelement of excessive longitudinal thrustswhich .would have tov be carried by the .thrustblock and which reducethe steam .pressure to the low pressure' re- 'quired to neutralize thepropeller-thrust;

and toemploy in the low pressure elementa drum pressure stage, having asteam tight pressure @head closing Ithe steam `space between' the'l1-'um ,andf the shaft, and producing afthri t opposed to the propellerthrust.

cated is Aopen lto the .erablenumber of e diaphragm andsteam spaceswhich increase the cost and length ofthe turbine, and, on account of theinaccessibility of tie diaphragm bushings, increasethe diiiic ilty andexpense of, repairs. By my presen 1 invention these obreversed and areso proj )ortioned relative to the steam pressuresthat the thrustproduced by one drumstage is pr Lctically neutralized by the otherdrumstage, andthe shaft thrust when present is also prf ctfioallyneutralized,

" jections are overcome by replacing the wheel Astages inthe high pres:ure element largely or partly by drum ress ire stages with steam jtightpressure hea s, wl Aich drum' stages are -65 at all substantial powers,'so thatthe thrust carriedfby the thrust bl( ck for this element ifany, ,is small in amo int. The propeller thrust is Wholly or'laigelyneutralized at all4 substantial element by a rsingle di rect drumpressure stage.,

'A further feature of t le present invention relates to means forvadusting the relative thrusts of the reversed drums in 'the highpressure element so as tc secure amore com- 'plete b alance in this elerLentr under different conditions of steam flow ind pressure. This isaccomplished by rov ding a by-pass for the steam, eontrolle by i. valve,around one or each of the drum stag es so as to vary the pressuredropbetween tl e ends of one or of c ach of 'such drum-stage; to suit theconditions of operation. y

Another feature of i Lvention relates to the| construction of theimproved turbine for a 4-shaft arrangemer t.- In carrying out this partof -the inventio i the turbine is divided into'four element; mounted ontwo shafts, .e., a high press ire element on one shaft, an intermediatepressure element on the other shaft of the sain( pressure element and ta[ring the full flow of steam from the hi h pressure element,

and two low pressure e ei cents` (one on each shaft) which receive-thsteam flow from owers in the low^pressurepowerA as the hightheintermediate pressur element in multiple. AThe high and intermediatepressure elements are balanced `wizhin themselves `by 'the use ofreversed druin pressure stages,

while the two low pressu e elements receive a low enough steam pre: sureto wholly or largely neutralize the ti'rust .of the propellers at allsubstantial )owers by the ernployment in each of a single directV drumpressure stage. ,y

The invention is illust ated'as embodied nal half section v,of afour-element i and 5),.

`through the stuffing boxes, producingshaft at 11, 12. The high pressureelement, as

in two forms of turbine, Figures 1 to 6 showing a turbine composed of ahigh and a low pressure element complete. on one shaft, and Fig. 7showing a turbine of four element divided between two shafts.

In the drawings, Fig. 1 is a side elevat-ion, of the high pressureelement of the turbine complete on one shaft, 'with the upper half inlongitudinal section on line -l-1 in Figs. 4 and 5;l Fig. 2 is alongitudinal sec- 'tion on line 2-2 in Figs. 4 and 5; Fig. 3 is aReferring particularly to Figs. 1 to 6,

A and B are respectively the high and low pressure elements of theturbine.' I will first describe the high pressure element of'itheone-shaftV form of turbine (Figs. 1, 2, 4 Its shaft scction'7 whichcarries the rot-ating partsis preferably stepped 'downto smallerdiameters where it passes thrust areas subject to the'steam pressures atthe ends of theshell.A The sides 'of the 'shell or` casing are shown at8, its forward andv aft heads at 9, 1() and the stuffing boxes shown, isprovided with two initial jet wheel stages. The nozzles 13- of the firststage are carried by .the head 9. The wh'el 14 Aof the first stagecarries, preferably, a plurality of Y' rows of moving buckets co-actingwith stationary intermediate buckets carried by the shell. Following thewheel 1.4 is a diaphragm 15 supported by the shell and having a bushingor packing surrounding the shaft. The space in front of the diaphragm 15is large enough to permit the removal and repair'of the bushing orpacking in segments, and access is oiven to' this space by I hand-holesor manholes 16 in the head. 9

and by `one or lnore Y openings 17 in the web ofthe wheel 14. The

. -dlaphragm 15 carries the second stage n ozzles '18, and .thesedeliver the 'steam tothe buckets' of the second jet wheel stagewhichar'e carried by the wheel 19 and by the shell.

The-wheel v19 is mounted upon the pressure' head'20 of the first' drumpressure stage,

. which pressure head is formed and propor- 60 shape'the difference inpressure to which it tioned so as to withstand without change of issubjected. The drum v21 of thejirst drum stage -is supported inl art-bythe'head 20 whlch' closes .steam tig t the space Abetween the drum and'the'shaft. 'The first 'drum' 'reaction principle.

stage carries the steam' in the same direction as the initial wheelstages and receives it directly from the second wheel stage. The' drumof the first drum stage carries a number of annular rows of bucketsseparated by annular rows 'of stationary buckets carried by the casing.TheseJ buckets operate on the impulse or on. the reaction principle. Ineither case there is a diffrence in steam pressure between the admissionand discharge ends of the drum stage which is effective on' the head'20to produce" an aft thrust on the shaft. As will be understood theadmission-V of steam tothe buckets of the rst drum stage is a completeperipheral one, vwhile at the wheel stages the nozzles occupy only'apart of the peripheries of the wheels. In passing through the wheelstages the steam is reduced in pressure and increasedin volume so that acomplete peripheral admission can be had atthe first drum stage withbuckets of a sufficient` radial depth to keep the tip clearance leakage'within permissible-limits. y

The radial dept-h of the buckets of the wheel stages can be made asvgreat-as desired because of the fact that a partial peripheraladmission e., jet admission) is employed in these stages." `The-use ofthe initial ]'et wheel-stages also results in a reduction in pressurewithin the casing head* to thatwhich can be practically controlled bythe shaft stuing box.

' Following the first drum stage, the steam space between the shell andthe shaftisV closed a diaphragm 22'having a bushing surrounding theshaft. A working space is provided in which this bushing or packing maybe-repaired or replaced in segments, which space isaccessible through aVcovered man-hole 'or hand-hole'231in the casing'.

The ldiaphragm 22 is made necessary because the steam flow is reversedthrough the second drum stage.' rIhe second drum' stage Vhas a' drum 24carrying` a number of :annular"rows. of buckets eo-acting witlrannularrows of intermediate buckets carried by the casing, andv operating r onthe impulse or In .either case, as with the first drumstage, there is adifference in steam pressurebetween 'the Aadmission and discharge endsof the'stage which'is effec- Ative on a steam tight pressure head *25closing the space between the .drum and' the shaft andformedand-proportioned to withstand the pressure difference to which it`is subjected without changcof'shape. The

steam is admitted to the aft end of the second' 'velocity stage bychannels 26 in the' Casing (Figs' 2, ,4 and 5) connecting the space'infrontof the diaphragni 22 with the A spaceaft of the pressure heady 25,while the steam-*discharged from this `stage into the space forwardofthe head 25 is carried back to the 'chamber 27 in" th'e aft head 1 0of the high pressure element by channels 28 (Figs. 1, 4 and 5). Thedifference in pressure on the shaft thrust areas and the ditf ference inpressure on the first drum stage produce an aft thrust oir the shaft,Whilepowers, so that the unbalanced thrust, if

any, will be small.l In order to secure a more complete balance of thethrusts under different conditions of operation acontrollable 'by-passmay be provided around one or each of the drum 4stages solas `to enablethe adjustment of the differences in pressure carried by the pressureheads 20 and 25. A pipe 29 having a valve 30 'performs thisoflice forthe irst drum stage, while an opening 3l (controlled by a' valve 32) he-`tween the chamber 27 and the admission side ofthe second drum stageserves toV 'shunt steam around the second drum stage.

The shaft section 7 of the high pressure element A, is connected withthe shaftv section 33 of the low pressure' element Bby a slip coupling34. The casing 35 of the Vlow pressure element has fore and aft heads36, 37, provided with stuiing boxes 3S, 39, preferably surroundingreduced diameters of the shaft. One or fmore pipes 40 convey the steamfrom the chamber 27 of the high pressure element tothe fore head of thelow pressure element, and have a slip A.or expansion joint 41 permittingthe relative movement ofy the two` elements. Within the casing of thelow pressure elementis a drum pressure stage havin a number of annularrows of moving and stationary buckets operating on the impulse orreactioujprirr ciple.` ,The drum 42 of this drum stage is supported fromthe shaft in part by a steam tigl'it pressureY head 43 formed andproportioned to withstand the difference 'in pres sure to which it issubjected without change of shape. The pressure head 48 is subjected.onl its forward side to the steam pressure existingat the admission endof the drum stage while its rear side is open to the eX- haust 44 andhence receives the exhaust pressure. i steam passage area through thisdruml stage4 and by giving it a proper thrust area, the thrust aftproduced by it wilTbalance practically, or reduce to a jjaacticablea'l'upunt,

at all powers, the forwardthrust of the` propeller (not shown.) which iscarried by the shaft Any llnl'ialanced thrust, one way or the other,will be small. ln Fig. 6

By properly1 proportioning .the

the 4high and low prf ssure l eleinents are shown assembled, the t'irustblocks 45,- 46, Afor the sections 7 and 33 oftheshaft being illustrated.These thru ltblocks may be located eitherat theyfor vard or aft end ofeither element. `The .reversing turbine is shown as "'"inclosed in tierear-end of the casing of the low pressi] re element'. As will beunderstood, it hasa. lrum pressure stage opposing the propeller hrust YThe yturbine shown in Figs. 1 to 6 is use-r ful in any arrangement ofone or more propeller shafts, in 'which' it is desired to ern-` ploy acomplete indepen lent turbine on each shaft.

A special constructi )n of the turbine adapted for a *fl-shaftarrangement is illustrated in Fig. J7, to Whic 1 reference -will now pbe made. The turbine is divided into four elements, C,'D', E and F. Theelements C andD are respectively iigh and intermediate pressureelements, tie latter taking the entire flow of steam fro n the former,while the elements E and F 2 re low pressure elements which receive thesteam from the intermediate pressure elerr ent in multiple, each `takingone-half the How of steam. The elements G and D are (f practicall equalpower, as likewise are tl e elements L and F,

.so that the power deve oped oneach shaft will be the same.'l The l woshaft sections of 47, 48, and the slip coup] llng connecting them isshown at 49. The hi` gh pressure elel'nent, shown, has one jetwheeljstage 50, al'- though it may have tw 3 or more, and two drumpressure stagesll and 52 separated by a diaphragm 53,`and co1 nected soas to have a reversed steam flow t v pipes or channels 54. Tiese drumstage; have steam tight pressure heads 55, .56, `vhich exert thrustsupon the shaft section 47. inopposite directions so to practicallyi.eutralize the thrust within the Ahigh pressurl element of the turbineat all sllljistantial powers, as described in connection with Vthe high`pressure element A. The j low pi `essure element E, which is mounted onth shaft section 48, is similar in constructipn, tothe low pressureelement B, already desc 'ibed, having a siu gledireet drum pressuri,stage proportioned with respect to the area of its steam passagestautial powers. The s laft sections 47 and 48, it will be understoo(are provided with 'the high pressure element are indicated atindependent thrust bloc lis, as illustrated inV Fig. 6. The intermedi:te pressure element l) receives` the `full tlow of steam from the highpressure element tirou'gh one or more rpipes 57. This element isprovided withy i two drum pressure stage having steam tight pressureheads 60 and Gl, separated by a diaphragm 62. .The d1 um pressure stages'58, 59 receive the steam flow 1n opposite d1- rections, the dischargeend of stage' 58 being connected with the head en d of stage 59 by steamchannels 63. The reversed drum pressure stages 58, -59 are proportionedso as to produce thrusts in opposite directions and to practicallyneutralize at all substantial powers the thrusts upon the shaft withinthis element of the turbine. The rotating parts of the elementv D aremounted upon 'the shaft section 64, which vis connected with the shaftsection 65 by a slip coupling 66. The low pressure element F, which ismounted on the4 shaft section 65, is similar to the low pressure elementE, having a single direct drum pressure stage with a steam tightpressure head adapted to practically neutralize the propeller thrust atall substantial loads. vided with independent thrust blocks Asimilar tothe shaft sections 47,1 48. rIhe exhaust from the intermediate pressureclement is divided between two pipesl G7, 68, which divide the steam iowbetween the two low pressure elements E and F, giving the large bucketareas required to pass the steam at the low pressure and large volumeexisting ncar the exhaust end of the turbine. It will be understood thatthe shafts shown in Fig. 7 are two shafts of a li-shaft arrangement, andthat the other two shafts will be provided with a similarly dividedturbine.

Vhat I claim is v l. In a marine steam turbine having elementsoperatedat different steam pressures mounted on the same shaft, the combinationof reversed drum pressure stages in one element, producing thrusts inopposite directions, and a drum pressure stage in the other elementproducing a thrust opposed to the propeller thrust, substantially ,asset forth.

2. In a marine steam turbine having elements operated at different steampressures mounted on the same shaft, the combination of one or moreinitial jet wheel stages and reversed drum stages in the higher pressureelement, the latter producing thrusts in opposite directions, and a drumpressure stage in the lower pressure element producing a thrust opposedto the propeller thrust, sub# stantially as set forth.

' 3. `In a-marine steam turbine, the combination of two elementsoperated at different steam pressures mounted en the same shaft, a slipcouplingl in the sha-ft between the elements permitting the independentlongitudinal movement of the two elements, separate lhrust blocks forthe two shaft sections, reversed drum pressure stages in the higher Theshaft sections 64, G5 are pro-V pressure element, producing thrusts inopposite directions, and a drum pressure stage in the lower pressureelement producing a thrust opposed to the propeller thrust, sub-vstantially as' set forth.

4. In a marine-steam turbine, thecombi- `nation of -a drum pressurestage at the eX- haust vend of the turbine producing a Ythrust opposedto and practically the same as the propeller thrust and preceding drumpres- ,I

sure stages reversed with respect to each other and producing oppositeand pr'afctif' cally equal thrusts', substantiallyas. set forth.

5.' In a steam turbine, the combination of reversed drum pressure stagesexerting thrusts 1n opposite direetlons, and a controllable by-pass forthe steam around one elements mounted on different 'shaftsfeachhavingreversed drum pressure stages pro.- ducing thrusts 1n oppositedirections and two low pressure elements mounted onthc,

different shafts and receiving the steam flow in multiple fromtheintermediate pressure element, each of said low pressure elementshaving a drum pressure stage producing a thrust opposed to the propellerthrust, substantially as set forth.

8. Ina marine steam turbine, the combi nation with two shafts, of a highApressure' turbine element on one shaft, an intermediate pressureturbine element having reversed drum pressure stages on the other shaftreceiving the full How vof steam from the high pressure element, and twolow pressure turbine elements mounted on the two shaft-s and receivingthe steam flow in multiple from the intermediate pressure element,substantiallyas set fort This specification signed and witnessed this15th day of November, 1910.l

CHARLES-e. sumas.

Witnesses:

yJOHN L. Lo'rsoH, GUsTAv A SoHELLAoK. Y

Copies of this patent may be obtained for ive cents each, by addressingthe Commissioner-of Patents,

../Washington, I). C.

